The purpose of this preliminary study was to determine whether oral interferon-alpha (IFN-a) has any definable effect on peripheral immunity in patients with relapsing-remitting multiple sclerosis. Each of ten subjects were given three dose levels of IFN-a 3 times weekly for 3 weeks. Establishment of safety, optimal dosages and specific immunological effects for orally administered IFN-a in subjects with RR MS will lead to a blinded placebo controlled Phase II trial. The results showed that IFN-a, at doses of 10,000, 30,000 and 100,000 units over 2 weeks, was 1) nontoxic, and 2) showed modification of biological response at 10,000 and 30,000 units. This will lead to the Phase II study "Oral interferon alpha: biologic effects in subjects with relapsing remitting multiple sclerosis", which will include enhanced MRI's as a primary outcome measure.